Acta Universitatis Sapientiae Electrical and Mechanical Engineering, 6 (2014) 3546 35 Vertical Handover and Load Balancing Decision Algorithms for Heterogeneous Cellular-WLAN Networks Zsolt Alfred POLGAR, Andrei Ciprian HOSU, Zsuzsanna Ilona KISS, Mihaly VARGA Department of Communications, Technical University of Cluj Napoca, Cluj Napoca, Romania e-mail: {Zsolt.Polgar; Andrei.Hosu; Zsuzsanna.Kiss; Mihaly.Varga}@com.utcluj.ro Manuscript received July 17, 2015; revised November 18, 2015. Abstract: Multi-access and heterogeneous wireless communications are one of the solutions for providing generalized mobility and improved user experience. This paper proposes Vertical Handover (VHO) and Load Balancing (LB) decision algorithms for heterogeneous network architectures which integrate cellular networks and Wireless Local Area Networks (WLANs). The cellular-WLAN VHO and LB decisions are taken based on parameters which characterize both the coverage and traffic load. Computer simulations performed in realistic scenarios show that the proposed VHO algorithm ensures better performance compared to “classical” ones and that the LB mechanism can significantly offload the congested cellular networks when WLAN connectivity is available. Keywords: ubiquitous connectivity, vertical handover, heterogeneous networks, decision algorithm, network state information, load balancing. 1. Introduction An important characteristic of Next Generation Networks will be the integration of heterogeneous wireless access technologies, which will lead to increased overall system efficiency and improved user experience. Several issues concerning service continuity and resource management are still unsolved and require further research. The authors of [1] present a survey of existing technologies that support multimedia communications in a heterogeneous wireless network and the main requirements and solutions for mobility management are discussed. In [2] the The results of this study were partially presented at the 5 th International Conference on Recent Achievements in Mechatronics, Automation, Computer Sciences and Robotics 2015.